OpenCV Image Blending

The function of OpenCV image mixing is:

cv2.addWeighted(src1, alpha, src2, beta, gamma, dst=..., dtype=...) -> dst

Required parameters:

• src1: numpy array of the first image.
• alpha: The weight of the first image.
• src2: numpy array of the second image.
• beta: The weight of the second image.
• gamma: A constant added after image blending.

Optional parameters:

• dst: numpy array of output images.
• dtype: The bit depth of the output image, the default is src1.depth().

The mixed formula can be expressed as follows:

$$\texttt{dst} (I)= \texttt{saturate} ( \texttt{src1} (I)* \texttt{alpha} + \texttt{src2} (I)* \texttt{beta} + \texttt{gamma} )$$

Example

The following example sets alpha + beta = 1.0, and gamma = 0.0. This example is also on my github repo. Press ESC after executing the script to exit the script.

import cv2


def main():
    img1 = cv2.imread("Dog_Strong.jpg")
    img2 = cv2.imread("Dog_Weak.jpg")
    window_name = "Blending"

    def change_trackbar(val):
        alpha = float(val / 255)
        blend_img = cv2.addWeighted(img2, alpha, img1, 1.0 - alpha, 0.0)
        cv2.imshow(window_name, blend_img)

    cv2.namedWindow(window_name)
    cv2.createTrackbar("trackbar", window_name, 0, 255, change_trackbar)
    cv2.imshow(window_name, img1)
    while True:
        if cv2.waitKey(100) == 27:  # ESC
            cv2.destroyWindow(window_name)
            break


if __name__ == "__main__":
    main()

Demo: